1. Field
The present disclosure relates to zoom lens systems, interchangeable lens apparatuses, and camera systems.
2. Description of the Related Art
In recent years, interchangeable-lens type digital camera systems (also referred to simply as “camera systems”, hereinafter) have been spreading rapidly. Such interchangeable-lens type digital camera systems realize: taking of high-sensitive and high-quality images; high-speed focusing and high-speed image processing after image taking; and easy replacement of an interchangeable lens apparatus in accordance with a desired scene. Meanwhile, an interchangeable lens apparatus having a zoom lens system that forms an optical image with variable magnification is popular because it allows free change of focal length without the necessity of lens replacement.
Zoom lens systems having excellent optical performance from a wide-angle limit to a telephoto limit have been desired as zoom lens systems to be used in interchangeable lens apparatuses. Various kinds of zoom lens systems each having a negative lens unit located closest to an object side, and a multiple-unit construction have been proposed.
Japanese Laid-Open Patent Publication No. 2005-092056 discloses a zoom lens having a four-unit construction of negative, positive, negative, and positive, wherein the interval between the first lens unit and the second lens unit decreases, the interval between the second lens unit and the third lens unit increases, and the interval between the third lens unit and the fourth lens unit decreases at a telephoto limit in comparison with at a wide-angle limit during zooming.
Japanese Laid-Open Patent Publication No. 2008-176271 discloses a variable magnification optical system having a four-unit construction of negative, positive, negative, and positive, wherein the interval between the second lens unit and the third lens unit increases, and the interval between the third lens unit and the fourth lens unit decreases during magnification change from a wide-angle limit to a telephoto limit, and wherein the whole of the third lens unit or a part of the third lens unit, as an image blur compensating lens unit, moves in a direction perpendicular to an optical axis.